Apparatus for spraying molten metal



July 13, 1954 R. M. BRENNAN APPARATUS FOR SPRAYING MOLTEN METAL Original Filed Jan. 15, 1948 INVENTOR. B W M M Patented July 13, 1954 APPARATUS FOR SPRAYING MOLTEN METAL Robert M. Brennan, Cleveland, Ohio Original application January 13, 1948, Serial No. 1,926. Divided and this application December 20, 1949, Serial No. 134,016

6 Claims.

This invention relates to the uniform depositing of metallic materials, especially to an apparatus for spraying molten metals to produce a uniform, thin, continuous sheet from same.

This application is a division of my copending application Ser. No. 1,926, filed January 13, 1948, now abandoned.

In the manufacture of many articles, such as thin metal sheets or foil to be used in the manufacture of condensers, it is very necessary to provide uniform sheets so that the electrical characteristics of the condenser in which the metal sheet or foil is used will be provided with uniform, non-changing electrical properties. Metal sheets or foil have heretofore been produced in some instances by spraying molten metal, such as aluminum, onto a paper or porous fibrous base which provides a binding material to aid in the deposit of molten metal in the formation of a thin metal sheet. In spraying metal onto a base member of the type indicated, or in otherwise forming metal sheets, as by spraying liquid metal onto a moving belt or other back-up member, it is diificult to effect a uniform spraying action. Many prior patentees have endeavored to secure uniform spray action by forcing metal from a container by a uniform gas pressure set up in the container, but I have learned that a varying metal pressure in such apparatus appreciably affects the uniform spray action desired. Furthermore, metal has usually been sprayed from spray guns, with the metal being supplied to the gun in the form of a strip or wire. Such guns are undesirable in that the strip or wire fed thereto is quite costly, and also the guns may be objectionable due to the cost of heating metal in the gun or in the method of ejecting metal from the gun.

The general object of the present invention is to avoid and overcome the foregoing disadvantages of known types of apparatus for spraying molten metal in a continuously uniform manner and to provide a metal spraying apparatus characterized by the low cost operation thereof and the uniformity of the deposit action.

Another object of the invention is to provide apparatus for spraying molten metal wherein a low cost raw material is used.

Another object of the invention is to utilize a constant pressure head in the spraying of molten metal.

A further object is to produce a wide metal strip by the use of a plurality of nozzles having laterally overlapping spray zones.

Yet another object of the invention is to provide automatic means for creating and maintaining a uniform pressure head in metal spray apparatus and to maintain such pressure head constant while metal is continuously withdrawn therefrom.

A further object of the invention is to provide apparatus for continuously spraying metal uniformly to produce a thin layer of metal which is uniform in gauge, porosity, density, width, flexibility, etc.

The foregoing and other objects and advantages of the invention will be made apparent as the specification proceeds.

In order to understand the process and apparatus of the invention, one embodiment of same is illustrated in conjunction with this specification. Attention is directed 'to the accompanying drawings which illustrate this embodi ment of the invention and wherein:

Fig. l is an elevation, partially in section, of apparatus embodying the principles of the invention;

Fig. 2 is a plan of the apparatus of Fig. l; and

Figs. 3 and 4 are end elevations of modifications of nozzles which may be used in the practice of the invention.

Reference is now made to the details of the embodiment of the invention illustrated in the drawings and apparatus In is provided for uniformly spraying molten metal. This apparatus of the invention may be used with substantially any metallic material and one use for the apparatus is the spraying of aluminum in the formation of lengthy, thin, uniform sheets therefrom for use in producing condensers, which sheets are in the vicinity of .005 in thickness.

The apparatus I0 mainly comprises a base duct or conduit II and a cover or inverted container ii that is carried by the base duct or pan H. In use of the apparatus, a pool of a molten metallic material 13 is positioned in the inverted container [2 and is retained therein due to an airtight joint being formed between the bottom of the container l2 and the duct ll. Normally, a charging door It is pivotally secured to the upper portion of the container l2 and may readily be swung upwardly thereof so as to permit the insertion of material l3 into the container. In many instances, it also is desirable to control the pressure or vacuum in the upper portion of the container l2 and to this end, a suitable pipe l5 connects to the container l2 and extends therefrom for connection to a valve or other control and pressure regulating means (not shown). The base duct H may be formed from any conventional material, usually a refractory, as is the container 2, with the only requirement being that these articles are not affected by the molten metallic material l3. Of course, the container and base duct are formed from higher melting point materials than the material 13. The base duct 1 i is supported in any conventional manner, as by beams l6.

Fig. 2 of the drawings best shows that the base duct l I has an extended portion or metal receiving section ll provided thereon. This extended portion ll is provided for receiving a constant pressure head of molten material and is adapted to have such constant pressure head maintained uniformly even though material is continuously l withdrawn therefrom. So as to permit flow material Hi from container l2, an outlet i8 is formed in the wall of the container l2 adjacent the extended portion ll of the base pan and means are associated with the outlet regulating flow of the material l3 therethrough. In this instance, a float type of valve device is provided for maintaining the material 23 at a predetermined level in the outer portion of the base duct ll.

l9 that has a lug 26 extending outwardly therefrom and the gate valve is adapted to be received within the container l2 and seal the outlet 53 when the valve is is seated on the inner surface of the container I2 adjacent the outlet i8. Fig. 1 shows that a shoulder 2| may be provided in the upper surface of the base duct H for the valve 5 3 to seat on when closing the outlet iii. A float 22 of conventional construction is provided for support on molten material in the extended por tion ll. This float 22 connects through a lever arm 23 to the lug on the gate valve is. A pin 2 t extends through the lever arm 23 and posi tions it pivotally on the bracket 25 on the container 52.

So as to deposit molten material from the apparatus Ill, at a uniform rate, a nozzle 26 is secured to the extended portion l! of the base duct 5 i in any conventional manner and it may extend outwardly from the base duct E l. The nozzle 26 may be provided with a coil 21 for heating and/or cooling the material passing through the nozzle 25, as required. Normally, the coils 27 are inductive coils supplied with high frequency electrical energy so as to heat the material in the nozzle 28 to predetermined temperatures or to maintain a desired temperature in the material so as to obtain desired fluidity therein. The passage of molten material from the nozzle 26 is usually facilitated by means of compressed gas. Thus a conduit 28 may be connected to a supply of compressed air or gas and this conduit connects to the lower end of the nozzle 28. A plurality of inwardly tapered bores or a hollow conical section 29 may be provided in the discharge end of the nozzle 26, all of which bores or conical section connect to the conduit 28 and receive compressed gas therefrom and may assist in the discharge of the molten material by a siphoning action.

Material contained in the inverted container l2 may be heated in any conventional manner, as by a high frequency induction coil 3i, which encompasses a portion or all of the periphery of the container.

Normally it is desirable to provide means for preventing flow of molten material from the apparatus should undesirable operating conditions exist. Hence a shut-01f float member 32 is carried on the surface of the material ill in the for This device includes a gate valve portion H of the base duct H. This float is supported by a rod 33 that is carried by a bracket 34 which extends out from the container l2 over and above the portion H. The rod 33 is positioned by the bracket 34 for sliding movement in a substantially vertical plane whereby the float 32 is permitted to move only vertically with relation to a valve seat 35 provided in the base duct H over the opening therein connecting to the bore of the nozzle 25. A counterweigl'rt 35 may be connected to the upper end of the rod 33 by means of a link 3? that is journaled on pin 38 carried by the bracket 34.

The nozzle 26 may be of any desired configuration and may be of round contour or section as shown in Fig. 1. However, in many instances, it is desirable to provide a wide spray of metal by the apparatus of the invention. Thus, 3 of the invention shows a nozzle member which has a wide, flat bore 42 provided therein with an air outlet 43 surrounding the bore F-lence, molten material issuing from the bores 42 can be blown into particles by an air blast issuing from the air outlet A53. The air stream from the air outlet 33 may be converging in toward the bore 32 of the nozzle, if desired. This type of con struction is indicated in Fig. 1 wherein the air streams from the bores 25 converge in on the bore of the nozzle so as to break up the material issuing therefrom into a stream of molten particles.

Fig. t shows another type of elongate nozzle which may be used in the practice of the invention. In this instance, a nozzle 5! is provided that has a plurality of transversely aligned but spaced bores 52 provided therein for permitting streams of metal to issue therefrom and an air outlet or outlets 53 are provided around the aligned bores 52. Again, the molten material issuing from the nozzle will be carried along and be broken into particles by the air stream and. will be caused to deposit on any desired surface in a uniform manner so as to produce a relatively wide strip.

Usually in the practice of the invention, the sprayed material is deposited on a moving base member which continuously withdraws the deposited material from the apparatus and provides a new surface for receiving the sprayed molten material in a continuous manner. Fig. 1 shows one type of a base member which may be provided for receipt of metal sprayed from the nozzle 26. This member comprises a continuous elongate band 5! which is carried by support rolls 63. The band 6| may be made from paper, or gauze or other fibre, or it could even be made from other substances, such as a metal band or roll, or glass or other material which will withstand the temperatures involved. When the band fil is formed from a porous material, usually the sprayed metal deposits thereon and is integrally bonded thereto Whereas if the band is formed from metal or other solid, smooth surfaced material, the deposited metal usually is removed from the backing sheet after the deposited metal or other material has solidified. Preferably the band 6! is retained at a temperature of from about 70 to 220 F. so as to aid in solidifying material deposited thereon rapidly. Fig. 1 also shows that a conical guard 66 may be positioned adjacent the end of the nozzle 26 intermediate it and the band M, which guard will prevent the entrance of any appreciable volume of air into association with the material being sprayed. Hence the spraying conditions can be made and retained uniformly at any desired temperature by preheating air or other gas supplied to the conduit 28. The temperature of the gas surrounding the sprayed material as it is supplied to the nozzle should be from about F. to 100 F. or higher so as to prevent cold shotting of the deposited material when aluminum is being sprayed to form condenser sheet material therefrom. This gas supply temperature keeps the atomization of the sprayed material eflicient and aids in the formation of fine particles from the sprayed material. Of course, the carrier gas temperature is raised as it becomes associated with the molten particles being sprayed. Ordinarily, the particles of aluminum being sprayed should be maintained at a temperature of from about 600 F. to 1100 F. as they move along through the guard 54. In some instances, it is necessary to heat the material being sprayed as it leaves the nozzle 26 and a high frequency coil #63 may surround the guard 64 for controlling the temperature of the molten material as it passes toward the band 6!. An exhaust flue 68 may be associated with the remote surface of the band 5! with relation to the nozzle 25 so as to withdraw carrier gas from the atmosphere surrounding the apparatus of the invention. A thermostat T may be provided in the exhaust flue E8 and be connected to suitable control means for regulating the temperature of gas supplied to the conduit 28 should the temperature of the exhaust gas be other than within a desired temperature range.

Of course, the speed of movement of the band it! may be regulated to any desired value and may be effected by any desired means. Control of the spraying velocity by means of the predetermined setting of the apparatus of the invention, together with the temperature controls for the sprayed material, will provide constant operating conditions whereby the thickness, flexibility and porosity of the strip produced by the deposited material will remain constant and uniform. The resultant strip will have a good tensile strength and the production of stiff material will be avoided due to the depositing conditions.

It may be desirable in some instances to enclose the entire apparatus iii in a pressure chamher which is partially indicated in dotted lines on the drawing. This enclosing chamber will then make it possible to adjust the pressure applied to the surface of the metallic material being retained in the extended portion ll of the base duct 5 i so that a further pressure control is pro vided for the desired constant pressure head. It has been indicated heretofore that normally a carrier gas is necessary and is supplied through the tube 28. However, in some instances, when a sunicient velocity is obtained, due to the pressure head of metal on the material supplied to the nozzle 26 and the nozzle size, a desirable spraying action may be obtained without the use of a carrier or propelling gas. It should be noted that the area of the gate opening it in the container I2 is larger than the area of the one or more nozzles being supplied with molten metal through such gate so as to maintain a desired pool of material in the portion 1'! of the base duct.

In Fig. 1 it is shown that a ladle may be provided within the container l2 and be mounted upon a spindle 1! that extends out through the wall of the container 1 2 and is supported thereby. This spindle ll has a crank 62 or other means associated with it for controlling its position. Metal to be sprayed then can be deposited in the ladle 60 at desired intervals or constantly and n a desired condition and then can be dropped into the container at intervals or constantly so as to prevent establishment of an undesirably large pressure head within the container.

It also is desirable to provide an overflow lip 59 for the base duct H and a storage tank it receives excess molten metallic material flowing from the duct II. This material may be returned to the container l2 by a pump in a conduit 56 connected between the tank and container. If necessary, the material may be heated when in the tank 14 to maintain it molten.

Of course, after a porous metal strip has been produced in accordance with the invention, the strip can be stretched, rolled, heat treated or processed in any other way, depending upon the desired use for the metallic material. Practice of the invention will result in the formation of continuous metal strips having uniform properties both longitudinally and transversely of the strip. The strip may be from about 3 to 30" wide and of any suitable thickness. It is thought that 10# of aluminum can produce about 12 feet of a strip 30 wide and .005" thick in one hour by use of a plurality of laterally aligned spray nozzles.

The deposited particles lose sufficient heat the instant that they strike the band 6! so as to be solidified thereby and deposit thereon. By con trolling the temperatures to the ranges indicated, the deposited particles will weld or fuse together to produce the strip desired.

Attention is directed to my copending application Serial No. 744,727 which discloses and claims in more detail means for controlling the temperature and velocity of the particles being deposited as they are in transit toward a base band on which they will deposit and solidify.

From the foregoing, it will be seen that the apparatus of the invention is adapted to maintain continuously a uniform pressure head of molten material l3 in the extended portion of the base duct. This uniform pressure head will permit a uniform spraying action to be achieved by use of a uniform pressure gas or air stream which is used in connection with the spray nozzle of the invention. By a uniform spraying action, a uniform article will be produced so that a thin metal foil or sheet can be obtained or other continuous uniform articles can be produced from a metallic material. As pointed out hereinbefore, control of the temperature of the material being deposited, control of temperature of the carrier gas, and regulation of the temperature of the band is! also contribute to the formation of a uniform article having uniform properties.

While several complete embodiments of the invention have been disclosed herein, it will be appreciated that modifications of these particular embodiments of the invention may be resorted to without departing from the scope of the invention as defined by the appended claims.

Having thus described my invention, what I claim is:

1. Apparatus for spraying molten metal comprising a container for molten metal, a spraying device through which molten metal from said container is adapted to flow for spraying from said device, and means for maintaining a predetermined uniform level of metal in said container for achieving uniform spraying results including a feeding unit controlled by the level of metal in said container for feeding molten metal thereinto and overflow means on said container maintaining such uniform level in the event that the rate of feeding of molten metal into said container exceeds the rate of spraying thereof by said device.

2. Apparatus for spraying molten metal comprising a container for molten metal, a spraying device through which molten metal from said container is adapted to flow for spraying from said device, means for maintaining a predetermined uniform level of metal in said container for achieving uniform spraying results including a feeding unit controlled by the level of metal in said container for feeding molten metal thereinto and overilow means on said container maintaining such uniform level in the event that the rate of feeding of molten metal into said container exceeds the rate of spraying thereof by said device, and shut-off means controlled by the level of metal to discontinue flow of molten metal from said container to said device in the event that the rate of spraying of the molten metal by said device exceeds the rate of feeding of molten metal into said container causing the level of the metal to drop below such uniform level.

3. The apparatus of claim 1 wherein a predetermined uniform gas pressure is maintained on the uniform level of molten metal in said container to cause uniform flow of the molten metal through said device.

4. Apparatus for spraying molten metal comprising a constant pressure molten metal supply means, a spraying device in communication with said means and operative to direct molten metal particles onto the surface of an article disposed in the path of the field of spray of the molten metal particles, and heating means encircling the field of spray and operative to maintain the metal particles in molten condition during the course of their travel from said device to the article surface being sprayed.

5. Apparatus for spraying molten metal comprising a discharge pool of molten metal, means for maintaining a constant hydrostatic head of molten metal therein, a discharge nozzle leading from said pool through which a solid stream of molten metal is adapted to flow for spraying onto the surface of an article in the path of the field of spray of the metal particles, temperature control means for maintaining the stream of molten metal flowing through said nozzle at a desired temperature thereby controlling the fluidity of the molten metal stream, and gaseous blast means for breaking up the molten metal stream issuing from said nozzle into small particles and for directing the metal particles against the surface of the article.

6. Apparatus for spraying molten metal cornprising a discharge pool of molten metal, means for maintaining a constant hydrostatic head of molten metal therein, a discharge nozzle leading from said pool through which a solid stream of molten metal is adapted to flow for spraying onto the surface of an article in the path of the field of spray of the metal particles, temperature control means for maintaining the stream of molten metal flowing through said nozzle at a desired temperature thereby controlling the fluidity of the molten metal stream for thereby spray discharging from said nozzle a uniform volume of metal per unit of time under such constant pressure and fluidity.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 806,460 Bucklin Dec. 5, 1905 1,179,762 Schoop Apr. 18, 1916 1,195,310 White et a1 Aug. 22, 1916 1,198,610 Blakeslee Sept. 19, 1916 1,262,134 Stolle Apr. 9, 1918 1,323,999 Baker Dec. 2, 1919 1,968,329 Taylor July 31, 1934 2,133,504 Forton Oct. 18, 1938 2,252,942 Mourer Aug. 19, 1941 

